- move paint to idle handlers
- check whether WMDestroyWidget() should first call WMUnmapWidget().
- check if its useful to add some WMBrowserSelectionDidChangeNotification
  (actually a pass-through for WMListSelectionDidChangeNotification).
  Or a delegate to be called when the list selection change.
- check which behavior is better for list selecting while scrolling
  (the #define behavior2 in wlist.c)


- optimize color allocation for repeated colors
- make it work in 8bpp
- optimize SystemFont allocation for repeated font sizes